If you've ever bought gasoline in Williamson County, there's a good chance you paid more at the pump than you would have in Nashville.

It's a pretty wide disparity. On Aug. 29, gas prices in Brentwood, Cool Springs and most of Franklin hit $2.99 a gallon, while prices in Nashville — excluding the downtown area — hovered between $2.52 and $2.83 on the higher end, according to Gasbuddy.com.

A variety of factors contribute to the ever-fluctuating costs of gasoline, but some in the industry say gas is likely higher in Williamson County due to simple supply and demand.

(Photo: Getty Images.)

Pricing strategies vary

While it may cost more to fill your tank in Williamson County, the higher prices tend to be concentrated near the interstate and in commercial areas.

It cost $2.95 a gallon last week near Berry Farms in Franklin. But a few miles to the east in the Arrington area, stations were charging only $2.69 a gallon.

Similarly, prices tend to cost more in Nashville depending on where you go. In areas downtown and near Vanderbilt University, stations charged up to $2.99 a gallon, while stations in South Nashville and Donelson rarely exceeded $2.60.

The average price for a gallon of gas in Davidson County on Thursday was $2.67, and was $2.85 in Williamson County.

Labor Day prices

If you're planning to travel over Labor Day weekend, the good news is there are no anticipated spikes in fuel prices before the holiday, Osborne said.

"That's typically the last travel holiday of the summer season," Osborne said. "In mid-September is when refineries start to make the switch over to the winter blend of gas, which is a little less expensive to produce than the summer blend."

In addition, retailers usually see demand for gasoline drop in the colder months because people aren't usually traveling as often as they would in the summer, she said.